Strain estimation in phase-sensitive optical coherence elastography.

Area of Science:

• Biomedical Optics
• Mechanical Engineering
• Medical Imaging

Background:

• Optical Coherence Elastography (OCE) is a promising technique for non-invasively measuring tissue mechanical properties.
• Accurate strain estimation is crucial for reliable elastography but remains a challenge in OCE.
• Existing strain estimation methods in OCE have limitations in sensitivity and dynamic range.

Purpose of the Study:

• To develop and validate a theoretical framework for strain estimation in OCE.
• To introduce and evaluate a novel weighted least squares (WLS) method for strain estimation in OCE.
• To compare the performance of WLS with traditional finite difference (FD) and ordinary least squares (OLS) methods.

Main Methods:

• Theoretical framework development based on statistical analysis of displacement measurements.
• Derivation of strain estimates using FD, OLS, and WLS methods.
• Experimental validation using tissue-mimicking phantoms and excised porcine airway samples.

Main Results:

• The WLS method demonstrated significant improvements in strain sensitivity: ~12 dB over FD and ~4 dB over OLS.
• Theoretical predictions for strain estimation accuracy were validated by experimental results.
• Elastograms of phantoms and porcine airways showed clear contrast based on sample elasticity.

Conclusions:

• The WLS method offers superior strain sensitivity and accuracy for OCE compared to FD and OLS.
• This framework and WLS method advance the capabilities of OCE for quantitative mechanical property mapping.
• The developed techniques enable improved visualization and characterization of tissue elasticity.